A Micro-Electro-Mechanical Systems (MEMS) device may have one or more offset mechanism elements that are oriented in an out-of-plane position (offset) with respect to its originally-formed mechanism layer. FIG. 1 is a cross section view of a prior art MEMS device 100 during fabrication with an offset mechanism element 102 that is moved to an out-of-plane position with respect to two other mechanism elements 104 and 106 that are oriented along the plane of their originally-formed mechanism layer 108. The offset mechanism element 102 is flexibly coupled to the mechanism element 104 with a flexure 110 to hold the offset mechanism element 102 in a desired position during various stages of the fabrication process.
The completed MEMS device 100 will have the offset mechanism element 102 anodically bonded to the bonding layer 112, which is typically glass or the like. During the fabrication process (prior to the fabrication process stage illustrated in FIG. 1), the offset mechanism element 102 is partially separated from the mechanism layer 108 using known techniques, such as etching and/or other suitable micromachining processes. A connection is maintained between elements 102 and 104 by a flexure represented by element 110. After separation, the offset mechanism element 102 is aligned with the other mechanism elements 104 and 106 along an originally-formed mechanism layer 108. At some point during the fabrication process, the offset mechanism element 102 is physically moved into an offset position so that it may be anodically bonded to the bonding layer 112. A tool 114, or other suitable means for moving the offset mechanism element 102, physically exerts a downward force, illustrated by the direction arrow 116, onto the offset mechanism element 102 to move it into its offset position. The flexure 110 facilitates the movement of the offset mechanism element 102 as the tool 114 pushes it downward to its offset position. The flexure 110 may remain or may be removed during later stages of the fabrication process depending upon the nature of the MEMS device 100.
Because of the physical size constraints associated with the tool 114, the size of the offset mechanism element 102 is limited so as to provide a sufficiently large contact area 118. The contact area 118 must be large enough so that the working end of the tool 114 may be positioned so as to come into contact with the contact area 118. Further, sufficient physical strength must be provided about the contact area 118 to provide adequate structural support to accommodate the applied force and to protect the offset mechanism element 102 against damage that may otherwise be caused by the tool 114.
Proper offsetting of the offset mechanism element 102 requires precise control of the tool 114. Highly accurate position and alignment of the tool 114 with respect to the offset mechanism element 102 is required so that the force is applied only to the offset mechanism element 102. And, the force applied by the tool 114 onto the offset mechanism element 102 must be precisely controlled to achieve the desired movement of the offset mechanism element 102 without imparting a damaging force onto the offset mechanism element 102.
In view of the size constraints associated with the contact area 118, and the control issues associated with the tool 114, it is appreciated that there is an inherent limit to the physical properties of the offset mechanism element 102. The offset mechanism element 102 must have sufficient structural strength to accommodate the applied force exerted by the tool 114 without sustaining damage. And, the offset mechanism element 102 must be large enough for the tool 114 to accurately contact the contact area 118. Thus, prior art MEMS fabrication processes that employ the tool 114 may be limiting in many instances as MEMS devices become increasingly more complex and smaller. Accordingly, it is desirable for an improved MEMS fabrication process that does not require the tool 114.